This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2002-054561, filed Feb. 28, 2002, the entire contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to a disk supporting apparatus, and in particular, to a disk supporting apparatus having magnetic disks, a spacer ring, and the like fixedly stacked together around a hub of a spindle motor, and a magnetic disk drive comprising this disk supporting apparatus.
2. Description of the Related Art
In general, a magnetic disk drive comprises magnetic disks, a spindle motor that rotationally supports and drives the magnetic disks, a carriage assembly supporting magnetic heads, a voice coil motor that drives the carriage assembly, a board unit, and the like, all these components being disposed in a case.
The spindle motor has a cylindrical hub around which a plurality of magnetic disks and a plurality of spacer rings are alternately stacked together. These magnetic disks and spacer rings are mounted at the outer periphery of the hub and sandwiched between a flange formed at one end of the hub and a clamp ring screwed to the other end of the hub.
With such a magnetic disk drive, the speed at which the magnetic disks are rotated must be increased to process data at high speed. Thus, in recent years, high-speed rotating magnetic disk drives have been studied. However, when magnetic disks rotate at high speed, a phenomenon called xe2x80x9cflutterxe2x80x9d occurs in which the magnetic disks are vibrated owing to a variation in air pressure. If flutter occurs, the magnetic heads are less precisely positioned relative to the corresponding magnetic disks. This prevents recording density from being improved.
To prevent this problem, a high-speed rotating magnetic disk drive has been proposed in which each of the magnetic disks has an outer diameter corresponding to that of a 2.5-inch magnetic disk and an inner diameter corresponding to that of a 3.5-inch magnetic disk so as to reduce the area of each disk which may be vibrated, thus increasing its natural frequency, while reducing the level of flutter.
However, most of the parts of this high-speed rotating magnetic disk drive are different from those commonly used in normal-speed rotating magnetic disk drives. This reduces productivity, while increasing manufacture costs.
An embodiment of the present invention may provide a disk supporting apparatus that reduces the vibration of a disk to allow a head to be more precisely positioned relative to the corresponding disks, while suppressing an increase in manufacture costs.
According to an aspect of the present invention, to attain this object, a disk supporting apparatus comprises a motor including a rotatable hub having a disk receiving portion at an outer periphery of an end of the hub; a plurality of disks each of which has an inner hole through which the hub is inserted, the disks being fitted around an outer periphery of the hub; a spacer ring having an inner hole through which the hub is inserted, the spacer ring being fitted around the outer periphery of the hub and being located between the disks; and a clamp member fixed to other end of the hub to clamp the disks and the spacer ring between the clamp member and the disk receiving portion.
The disk receiving portion and the clamp member have a substantially equal outer diameter. The spacer ring has a larger outer diameter than those of the disk receiving portion and clamp member. If the outer peripheral radius of the spacer ring is defined as rs, the outer peripheral radius of each of the disks is defined as rd, the inner peripheral radius of the disk is defined as rh, and the outer peripheral radius of the disk receiving portion and clamp member is defined as rc, the rs, rd, rh, rc have a relationship:
(rcxe2x88x92rh)/rd less than 0.1 less than (rsxe2x88x92rh)/rd less than 0.15. 
According to another aspect of the present invention, a magnetic disk drive comprises the above described disk supporting apparatus which supports and rotationally drives magnetic disks; magnetic heads configured to record and reproduce information on and from the corresponding magnetic disks; and a carriage assembly which support the magnetic heads so as to be movable relative to the corresponding magnetic disks.
According to the disk supporting apparatus and magnetic disk drive configured as described above, when the outer peripheral radius of the spacer ring is defined as rs, the outer peripheral radius of each of the disks is defined as rd, the inner peripheral radius of the disk is defined as rh, and the outer peripheral radius of the disk receiving portion and clamp member is defined as rc, the above relationship is established. This enables the radius of a fixed portion of the disk and the natural frequency of the disk to be increased without changing the hub and the clamp member. Consequently, even if the disk is rotated at high speed, its vibration can be reduced to allow the corresponding head to be precisely positioned relative to the disk.
Additional embodiments and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The embodiments and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.